Xenophrys serchhipii

Raj, Prudhvi & Lalremsanga, Hmar Tlawmte, 2022, Larval descriptions of Rhacophorus bipunctatus and Xenophrys serchhipii from Northeast India, Zootaxa 5092 (4), pp. 493-500 : 494-497

Xenophrys serchhipii

Larval description. Morphological description of the tadpole is based on tadpoles at Stage 36 ( Fig. 3 ). Body robust, oval in dorsal and conical in lateral views respectively; maximum body diameter at mid length of the body; body length 27.8% of total length; snout rounded in dorsal and lateral views. Eyes large, positioned almost laterally and not visible in ventral view; eyes oriented laterally. Nostrils placed wide apart and almost to the lateral corners, round to oval opening in dorsolateral view; ornamentation observed along the margin of the narial opening with an elevated narial projection; inter-nostril distance 86% of inter-orbital distance; nostril placed close to the eye with eye-nostril distance corresponding to 35% of nostril-snout distance. Spiracle sinistral and posterolaterally oriented; spiracle tall, tubular with the inner wall attached to the body integument; opening free and oval, and located way below the mid-body. Tail robust and long; maximum height of the tail at mid length; tail length about 72% of the total length; tail musculature with the broadest width about 57% of the maximum body width; height of the tail musculature greatest at Body-tail junction and tapering to a pointed tip; height of the fins low; dorsal fin originating posterior to body-tail junction and ventral fin at ventral terminus; fins parallel to the tail muscle, with the dorsal fin higher than the ventral fin. Vent tube median and not attached to the ventral fin. Oral disc terminal and upturned; labia expanded vertically forming a dorsally oriented funnel ( Fig. 3D ); not emarginated with the lateral corners prominent. Oral disc width 96% of maximum body width; marginal papillae absent. Numerous long finger like submarginal papillae uniformly spaced across the oral disc. No keratinized structures present on the labia. Jaw sheaths weakly keratinized with fine serrations; lower jaw sheath broadly arch-shaped, upper sheath wide and straight. In preservative, the body and the tail musculature are dark brown; tail fins are opaque and speckled that continue till the tip of the tail; the oral disc and the fins are immaculate and translucent; gular, abdominal and lateral body region translucent and grey; gut coils visible.

Buccopharyngeal morphology (Stage 36). Buccal roof trapezoid and elongated ( Fig. 4A ). Prenarial arena with an elongated U-shaped ridge and with the anterior tips of the ridge broadened. Internal nares linear and oriented at 30° of the transversal plan; anterior narial wall low and smooth, with a small papilla located at the inner end; posterior wall elevated and smooth with a projection at the center. Postnarial arena bordered with two medially curved papillae. Median ridge tall and elongated reaching the prenarial ridge. A long and broad anteriorly pointed lateral ridge papillae with irregular margin is present lateral to the median ridge on each side. Buccal roof arena absent, with ~60 pustulations scattered. Glandular zone not evident. Dorsal velum smooth and divided medially. Buccal floor triangular ( Fig. 4B ). Prelingual area with three pairs of infralabial papillae: two pairs of large, broad and thick papillae located along the corners with the anterior papillae longer and broader than other papillae, and a third pair of tubular papillae located postero-medially. Tongue anlage distinct and prominent with no lingual papillae. Buccal floor arena absent, the area being delineated by a ridge on either side; about 4–6 pustulations placed irregularly on each side. Buccal pockets oriented transversely. Ventral velum smooth, with a wavy margin and no median notch. Glottis exposed a little posterior to the ventral velum.

Morphological features of Rhacophorus bipunctatus and Xenophrys serchhipii are similar with characters attributed to pond-type Rhacophorus ( Vassilieva et al. 2016; Grosjean & Inthara 2016) and neustonic Xenophrys tadpoles ( Inger 1985; Grosjean 2003) respectively. External characters of R. bipunctatus larvae consistent with other Rhacophorus tadpoles are: an anteroventral oral disc with many labial tooth rows and strongly keratinized jaw sheaths, an ovoid body with dorsolaterally oriented eyes, a sinistral spiracle and vent tube opening dextrally with a robust muscular tail, all characters of a typical benthic feeding larval morphotype ( Altig & Johnston 1989). Fei (1999), Fei et al. (2009) and Inger et al. (1999) described the LTRF of R. bipunctatus as 6(5)/3 or 6(5)/3(l). However, our observations highlight a continuous second upper tooth row. Similarly, external characters of X. serchhipii larvae that are consistent with other Xenophrys tadpoles are: a dorsally oriented umbelliform oral disc with weakly keratinized jaw sheaths and labial tooth rows absent, ovoid body with large laterally oriented eyes, sinistral spiracle and a medially opening vent tube with a sharply pointed slender tail, all characters of a typical neustonic surface feeding larval morphotype ( Inger 1983, 1985; Altig & Johnston 1989; Grosjean 2003; Deuti et al. 2017; Tapley et al. 2020). Comparisons of buccopharyngeal morphology with related tadpoles also reveal broad similarities ( Huang et al. 1991; Grosjean 2003; Grosjean & Inthara 2016). In Rhacophorus , shared traits are: prenarial arena bearing a broad discontinuous prenarial ridge; anterior narial wall bearing projections; a pair of elongated postnarial papillae oriented medially; presence of an elevated median ridge; buccal roof arena delimited by buccal roof arena papillae; presence of glandular zone; broad buccal floor; prelingual arena bearing infralabial papillae; tongue anlage with lingual papillae; buccal floor arena delineated by buccal floor arena papillae and pustulations; oblique buccal pockets; ventral velum with projections on margin of velum; glottis exposes behind the velum. Distinctive features of R. bipunctatus are the prenarial ridge as small, aligned protuberances; buccal roof arena delineated by seven pairs of buccal roof arena papillae; a continuous dorsal velum; four pairs of infralabial papillae with the third pair bifid; buccal floor arena delineated by 12 buccal floor arena papillae. Similarly in X. serchhipii , shared traits with tadpoles belonging to the genus Megophrys sensu lato are: an elongated trapezoid shaped buccal roof and buccal floor; a broad semicircular prenarial ridge; medially curved elongated postnarial papillae; an elongated median ridge reaching the prenarial ridge; elongated lateral ridge papillae; bucccal roof arena absent; a medially divided ventral velum; broad and thick infralabial papillae; buccal floor arena absent; transversely oriented buccal pockets. Distinctive features of X. serchhipii are: prenarial ridge with broadened anterior tips; three pairs of large, broad and thick infralabial papillae with the anterior papillae longer and broader. As to Xenophrys and those of genus Megophrys sensu lato, previous studies report the absence of tongue anlage in X. minor ( Wassersug 1980) and Megophrys nasuta ( Inger 1985) , but Grosjean (2003) reported the presence of tongue anlage in tadpoles of M. microstoma . In the current study, we report the presence of tongue anlage in X. serchhipii .

PR would like to thank the Director, Wildlife Institute of India for permitting the author to use facilities at Teaching lab, Wildlife Institute of India. PR would also like to thank the Department of Biotechnology Research Associate fellowship programme, India for funding the current work. A word of appreciation to technical officers Vinod Thakur and Rakesh for their timely help. HTL would like to express his sincere thanks to the Chief Wildlife Warden, Environment, Forests and Climate Change Department, Government of Mizoram, India for providing collection permission (Permission No. A.33011/2/99-CWLW/225) of Mizoram herpetofauna, Vabeiryureilai Mathipi, Lal Biakzual and Lal Muansanga for their assistance in the field and laboratory.

Figures

FIGURE 3. Tadpole of Xenophrys serchhipii (Stage 35); (A) Lateral view; (B) Dorsal view; (C) Ventral view (scale bar = 10 mm); (D) Oral disc, dorsal view (scale bar = 1 mm).

FIGURE 4. Buccopharyngeal cavity of Xenophrys serchhipii (Stage 36): (A) Buccal roof; (B) Buccal floor. BF buccal floor, BP buccal pockets, BR buccal roof, DV dorsal velum, G glottis, GF gill filters, IN internal nares, IP infralabial papillae, LRP lateral ridge papillae, MR median ridge, NVP narial valve projection, OD oral disc, PNA prenarial arena, TA tongue anlage, VV ventral velum.